Power Quality Analyzer Model 8335
113
APPENDIX A
MATHEMATICAL FORMULAS FOR VARIOUS PARAMETERS
NOTE the following abbreviations used in this section:
NSHC =
number of samples per half cycle (between two consecutive
zeros)
NSC =
number of samples per cycle
NSS =
number of samples in a second (multiple of NSC)
V =
voltage phase to neutral
U =
voltage phase to phase
RMS values of half-cycle voltage and current
(excluding neutral)
[]
[][ ]
1
Vhalf
:
2
∑
⋅
=
Next Zero
Zero
n
n
i
V
NSHC
i
Single rms voltage half-period i + 1 phase
[]
[][ ]
1
Uhalf
Compound rms voltage half-period i + 1 phase
:
2
∑
⋅
=
Next Zero
Zero
n
n
i
U
NSHC
i
[]
[][ ]
1
Ahalf
:
2
∑
⋅
=
Next Zero
Zero
n
n
i
A
NSHC
i
Rms current half-period i + 1 phase
n: sample (0; 255)
i: phase (0; 1; 2)
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